From 40b9d523a07cf5d146b3be2724c58e9e872a0836 Mon Sep 17 00:00:00 2001 From: Chuck Lever Date: Sat, 28 Jul 2007 17:51:00 -0400 Subject: [PATCH 1/1] libnfs.a: eliminate another dependency on a global variable The file support/nfs/fstab.c, which is linked into libnfs.a, depends on the global variable "verbose." This variable is defined and used only in the mount command, and the functions in fstab.c are used only by the mount command. Move fstab.c and support/include/fstab.h to utils/mount. This file placement is also consistent with at least one other mount helper, mount.ocfs2. Signed-off-by: Chuck Lever Signed-off-by: Neil Brown --- support/include/Makefile.am | 1 - support/nfs/Makefile.am | 2 +- utils/mount/Makefile.am | 4 +- utils/mount/fstab.c | 555 +++++++++++++++++++++++ {support/include => utils/mount}/fstab.h | 0 5 files changed, 558 insertions(+), 4 deletions(-) create mode 100644 utils/mount/fstab.c rename {support/include => utils/mount}/fstab.h (100%) diff --git a/support/include/Makefile.am b/support/include/Makefile.am index 69c4503..718abda 100644 --- a/support/include/Makefile.am +++ b/support/include/Makefile.am @@ -4,7 +4,6 @@ SUBDIRS = nfs rpcsvc sys noinst_HEADERS = \ exportfs.h \ - fstab.h \ ha-callout.h \ misc.h \ nfs_mntent.h \ diff --git a/support/nfs/Makefile.am b/support/nfs/Makefile.am index 82353a9..87f3949 100644 --- a/support/nfs/Makefile.am +++ b/support/nfs/Makefile.am @@ -4,7 +4,7 @@ noinst_LIBRARIES = libnfs.a libnfs_a_SOURCES = exports.c rmtab.c xio.c rpcmisc.c rpcdispatch.c \ xlog.c xcommon.c wildmat.c nfssvc.c nfsclient.c \ nfsexport.c getfh.c nfsctl.c \ - svc_socket.c cacheio.c closeall.c fstab.c nfs_mntent.c + svc_socket.c cacheio.c closeall.c nfs_mntent.c MAINTAINERCLEANFILES = Makefile.in diff --git a/utils/mount/Makefile.am b/utils/mount/Makefile.am index be83e2c..a5d7292 100644 --- a/utils/mount/Makefile.am +++ b/utils/mount/Makefile.am @@ -9,10 +9,10 @@ man5_MANS = nfs.man sbin_PROGRAMS = mount.nfs EXTRA_DIST = nfsmount.x $(man8_MANS) $(man5_MANS) -mount_nfs_SOURCES = mount.c error.c network.c \ +mount_nfs_SOURCES = mount.c error.c network.c fstab.c \ nfsmount.c nfs4mount.c \ nfsumount.c \ - mount_constants.h error.h network.h \ + mount_constants.h error.h network.h fstab.h \ nfs4_mount.h nfs_mount4.h mount_nfs_LDADD = ../../support/nfs/libnfs.a \ diff --git a/utils/mount/fstab.c b/utils/mount/fstab.c new file mode 100644 index 0000000..6ac5c70 --- /dev/null +++ b/utils/mount/fstab.c @@ -0,0 +1,555 @@ +/* 1999-02-22 Arkadiusz Mi¶kiewicz + * - added Native Language Support + * Sun Mar 21 1999 - Arnaldo Carvalho de Melo + * - fixed strerr(errno) in gettext calls + * + * 2006-06-08 Amit Gud + * - Moved code to nfs-utils/support/nfs from util-linux/mount. + */ + +#include +#include +#include +#include +#include +#include +#include + +#include "fstab.h" +#include "xcommon.h" +#include "nfs_mntent.h" +#include "nfs_paths.h" +#include "nls.h" + +#define LOCK_TIMEOUT 10 +#define streq(s, t) (strcmp ((s), (t)) == 0) +#define PROC_MOUNTS "/proc/mounts" + +extern int verbose; + +/* Information about mtab. ------------------------------------*/ +static int have_mtab_info = 0; +static int var_mtab_does_not_exist = 0; +static int var_mtab_is_a_symlink = 0; + +static void +get_mtab_info(void) { + struct stat mtab_stat; + + if (!have_mtab_info) { + if (lstat(MOUNTED, &mtab_stat)) + var_mtab_does_not_exist = 1; + else if (S_ISLNK(mtab_stat.st_mode)) + var_mtab_is_a_symlink = 1; + have_mtab_info = 1; + } +} + +int +mtab_does_not_exist(void) { + get_mtab_info(); + return var_mtab_does_not_exist; +} + +static int +mtab_is_a_symlink(void) { + get_mtab_info(); + return var_mtab_is_a_symlink; +} + +int +mtab_is_writable() { + int fd; + + /* Should we write to /etc/mtab upon an update? + Probably not if it is a symlink to /proc/mounts, since that + would create a file /proc/mounts in case the proc filesystem + is not mounted. */ + if (mtab_is_a_symlink()) + return 0; + + fd = open(MOUNTED, O_RDWR | O_CREAT, 0644); + if (fd >= 0) { + close(fd); + return 1; + } else + return 0; +} + +/* Contents of mtab and fstab ---------------------------------*/ + +struct mntentchn mounttable; +static int got_mtab = 0; +struct mntentchn fstab; +static int got_fstab = 0; + +static void read_mounttable(void); +static void read_fstab(void); + +static struct mntentchn * +mtab_head(void) +{ + if (!got_mtab) + read_mounttable(); + return &mounttable; +} + +static struct mntentchn * +fstab_head(void) +{ + if (!got_fstab) + read_fstab(); + return &fstab; +} + +#if 0 +static void +my_free(const void *s) { + if (s) + free((void *) s); +} + +static void +discard_mntentchn(struct mntentchn *mc0) { + struct mntentchn *mc, *mc1; + + for (mc = mc0->nxt; mc && mc != mc0; mc = mc1) { + mc1 = mc->nxt; + my_free(mc->m.mnt_fsname); + my_free(mc->m.mnt_dir); + my_free(mc->m.mnt_type); + my_free(mc->m.mnt_opts); + free(mc); + } +} +#endif + +static void +read_mntentchn(mntFILE *mfp, const char *fnam, struct mntentchn *mc0) { + struct mntentchn *mc = mc0; + struct mntent *mnt; + + while ((mnt = nfs_getmntent(mfp)) != NULL) { + if (!streq(mnt->mnt_type, MNTTYPE_IGNORE)) { + mc->nxt = (struct mntentchn *) xmalloc(sizeof(*mc)); + mc->nxt->prev = mc; + mc = mc->nxt; + mc->m = *mnt; + mc->nxt = mc0; + } + } + mc0->prev = mc; + if (ferror(mfp->mntent_fp)) { + int errsv = errno; + nfs_error(_("warning: error reading %s: %s"), + fnam, strerror (errsv)); + mc0->nxt = mc0->prev = NULL; + } + nfs_endmntent(mfp); +} + +/* + * Read /etc/mtab. If that fails, try /proc/mounts. + * This produces a linked list. The list head mounttable is a dummy. + * Return 0 on success. + */ +static void +read_mounttable() { + mntFILE *mfp; + const char *fnam; + struct mntentchn *mc = &mounttable; + + got_mtab = 1; + mc->nxt = mc->prev = NULL; + + fnam = MOUNTED; + mfp = nfs_setmntent (fnam, "r"); + if (mfp == NULL || mfp->mntent_fp == NULL) { + int errsv = errno; + fnam = PROC_MOUNTS; + mfp = nfs_setmntent (fnam, "r"); + if (mfp == NULL || mfp->mntent_fp == NULL) { + nfs_error(_("warning: can't open %s: %s"), + MOUNTED, strerror (errsv)); + return; + } + if (verbose) + printf (_("mount: could not open %s - " + "using %s instead\n"), + MOUNTED, PROC_MOUNTS); + } + read_mntentchn(mfp, fnam, mc); +} + +static void +read_fstab() +{ + mntFILE *mfp = NULL; + const char *fnam; + struct mntentchn *mc = &fstab; + + got_fstab = 1; + mc->nxt = mc->prev = NULL; + + fnam = _PATH_FSTAB; + mfp = nfs_setmntent (fnam, "r"); + if (mfp == NULL || mfp->mntent_fp == NULL) { + int errsv = errno; + nfs_error(_("warning: can't open %s: %s"), + _PATH_FSTAB, strerror (errsv)); + return; + } + read_mntentchn(mfp, fnam, mc); +} + +/* + * Given the directory name NAME, and the place MCPREV we found it last time, + * try to find more occurrences. + */ +struct mntentchn * +getmntdirbackward (const char *name, struct mntentchn *mcprev) { + struct mntentchn *mc, *mc0; + + mc0 = mtab_head(); + if (!mcprev) + mcprev = mc0; + for (mc = mcprev->prev; mc && mc != mc0; mc = mc->prev) + if (streq(mc->m.mnt_dir, name)) + return mc; + return NULL; +} + +/* + * Given the device name NAME, and the place MCPREV we found it last time, + * try to find more occurrences. + */ +struct mntentchn * +getmntdevbackward (const char *name, struct mntentchn *mcprev) { + struct mntentchn *mc, *mc0; + + mc0 = mtab_head(); + if (!mcprev) + mcprev = mc0; + for (mc = mcprev->prev; mc && mc != mc0; mc = mc->prev) + if (streq(mc->m.mnt_fsname, name)) + return mc; + return NULL; +} + +/* Find the dir FILE in fstab. */ +struct mntentchn * +getfsfile (const char *file) +{ + struct mntentchn *mc, *mc0; + + mc0 = fstab_head(); + for (mc = mc0->nxt; mc && mc != mc0; mc = mc->nxt) + if (streq(mc->m.mnt_dir, file)) + return mc; + return NULL; +} + +/* Find the device SPEC in fstab. */ +struct mntentchn * +getfsspec (const char *spec) +{ + struct mntentchn *mc, *mc0; + + mc0 = fstab_head(); + for (mc = mc0->nxt; mc && mc != mc0; mc = mc->nxt) + if (streq(mc->m.mnt_fsname, spec)) + return mc; + return NULL; +} + +/* Updating mtab ----------------------------------------------*/ + +/* Flag for already existing lock file. */ +static int we_created_lockfile = 0; +static int lockfile_fd = -1; + +/* Flag to indicate that signals have been set up. */ +static int signals_have_been_setup = 0; + +/* Ensure that the lock is released if we are interrupted. */ +extern char *strsignal(int sig); /* not always in */ + +static void +handler (int sig) { + die(EX_USER, "%s", strsignal(sig)); +} + +static void +setlkw_timeout (int sig) { + /* nothing, fcntl will fail anyway */ +} + +/* Remove lock file. */ +void +unlock_mtab (void) { + if (we_created_lockfile) { + close(lockfile_fd); + lockfile_fd = -1; + unlink (MOUNTED_LOCK); + we_created_lockfile = 0; + } +} + +/* Create the lock file. + The lock file will be removed if we catch a signal or when we exit. */ +/* The old code here used flock on a lock file /etc/mtab~ and deleted + this lock file afterwards. However, as rgooch remarks, that has a + race: a second mount may be waiting on the lock and proceed as + soon as the lock file is deleted by the first mount, and immediately + afterwards a third mount comes, creates a new /etc/mtab~, applies + flock to that, and also proceeds, so that the second and third mount + now both are scribbling in /etc/mtab. + The new code uses a link() instead of a creat(), where we proceed + only if it was us that created the lock, and hence we always have + to delete the lock afterwards. Now the use of flock() is in principle + superfluous, but avoids an arbitrary sleep(). */ + +/* Where does the link point to? Obvious choices are mtab and mtab~~. + HJLu points out that the latter leads to races. Right now we use + mtab~. instead. Use 20 as upper bound for the length of %d. */ +#define MOUNTLOCK_LINKTARGET MOUNTED_LOCK "%d" +#define MOUNTLOCK_LINKTARGET_LTH (sizeof(MOUNTED_LOCK)+20) + +void +lock_mtab (void) { + int tries = 100000, i; + char linktargetfile[MOUNTLOCK_LINKTARGET_LTH]; + + at_die = unlock_mtab; + + if (!signals_have_been_setup) { + int sig = 0; + struct sigaction sa; + + sa.sa_handler = handler; + sa.sa_flags = 0; + sigfillset (&sa.sa_mask); + + while (sigismember (&sa.sa_mask, ++sig) != -1 + && sig != SIGCHLD) { + if (sig == SIGALRM) + sa.sa_handler = setlkw_timeout; + else + sa.sa_handler = handler; + sigaction (sig, &sa, (struct sigaction *) 0); + } + signals_have_been_setup = 1; + } + + sprintf(linktargetfile, MOUNTLOCK_LINKTARGET, getpid ()); + + i = open (linktargetfile, O_WRONLY|O_CREAT, 0); + if (i < 0) { + int errsv = errno; + /* linktargetfile does not exist (as a file) + and we cannot create it. Read-only filesystem? + Too many files open in the system? + Filesystem full? */ + die (EX_FILEIO, _("can't create lock file %s: %s " + "(use -n flag to override)"), + linktargetfile, strerror (errsv)); + } + close(i); + + /* Repeat until it was us who made the link */ + while (!we_created_lockfile) { + struct flock flock; + int errsv, j; + + j = link(linktargetfile, MOUNTED_LOCK); + errsv = errno; + + if (j == 0) + we_created_lockfile = 1; + + if (j < 0 && errsv != EEXIST) { + (void) unlink(linktargetfile); + die (EX_FILEIO, _("can't link lock file %s: %s " + "(use -n flag to override)"), + MOUNTED_LOCK, strerror (errsv)); + } + + lockfile_fd = open (MOUNTED_LOCK, O_WRONLY); + + if (lockfile_fd < 0) { + int errsv = errno; + /* Strange... Maybe the file was just deleted? */ + if (errno == ENOENT && tries-- > 0) { + if (tries % 200 == 0) + usleep(30); + continue; + } + (void) unlink(linktargetfile); + die (EX_FILEIO, _("can't open lock file %s: %s " + "(use -n flag to override)"), + MOUNTED_LOCK, strerror (errsv)); + } + + flock.l_type = F_WRLCK; + flock.l_whence = SEEK_SET; + flock.l_start = 0; + flock.l_len = 0; + + if (j == 0) { + /* We made the link. Now claim the lock. */ + if (fcntl (lockfile_fd, F_SETLK, &flock) == -1) { + if (verbose) { + int errsv = errno; + printf(_("Can't lock lock file %s: %s\n"), + MOUNTED_LOCK, strerror (errsv)); + } + /* proceed anyway */ + } + (void) unlink(linktargetfile); + } else { + static int tries = 0; + + /* Someone else made the link. Wait. */ + alarm(LOCK_TIMEOUT); + if (fcntl (lockfile_fd, F_SETLKW, &flock) == -1) { + int errsv = errno; + (void) unlink(linktargetfile); + die (EX_FILEIO, _("can't lock lock file %s: %s"), + MOUNTED_LOCK, (errno == EINTR) ? + _("timed out") : strerror (errsv)); + } + alarm(0); + /* Limit the number of iterations - maybe there + still is some old /etc/mtab~ */ + ++tries; + if (tries % 200 == 0) + usleep(30); + if (tries > 100000) { + (void) unlink(linktargetfile); + close(lockfile_fd); + die (EX_FILEIO, _("Cannot create link %s\n" + "Perhaps there is a stale lock file?\n"), + MOUNTED_LOCK); + } + close(lockfile_fd); + } + } +} + +/* + * Update the mtab. + * Used by umount with null INSTEAD: remove the last DIR entry. + * Used by mount upon a remount: update option part, + * and complain if a wrong device or type was given. + * [Note that often a remount will be a rw remount of / + * where there was no entry before, and we'll have to believe + * the values given in INSTEAD.] + */ + +void +update_mtab (const char *dir, struct mntent *instead) +{ + mntFILE *mfp, *mftmp; + const char *fnam = MOUNTED; + struct mntentchn mtabhead; /* dummy */ + struct mntentchn *mc, *mc0, *absent = NULL; + + if (mtab_does_not_exist() || !mtab_is_writable()) + return; + + lock_mtab(); + + /* having locked mtab, read it again */ + mc0 = mc = &mtabhead; + mc->nxt = mc->prev = NULL; + + mfp = nfs_setmntent(fnam, "r"); + if (mfp == NULL || mfp->mntent_fp == NULL) { + int errsv = errno; + nfs_error (_("cannot open %s (%s) - mtab not updated"), + fnam, strerror (errsv)); + goto leave; + } + + read_mntentchn(mfp, fnam, mc); + + /* find last occurrence of dir */ + for (mc = mc0->prev; mc && mc != mc0; mc = mc->prev) + if (streq(mc->m.mnt_dir, dir)) + break; + if (mc && mc != mc0) { + if (instead == NULL) { + /* An umount - remove entry */ + if (mc && mc != mc0) { + mc->prev->nxt = mc->nxt; + mc->nxt->prev = mc->prev; + free(mc); + } + } else { + /* A remount */ + mc->m.mnt_opts = instead->mnt_opts; + } + } else if (instead) { + /* not found, add a new entry */ + absent = xmalloc(sizeof(*absent)); + absent->m = *instead; + absent->nxt = mc0; + absent->prev = mc0->prev; + mc0->prev = absent; + if (mc0->nxt == NULL) + mc0->nxt = absent; + } + + /* write chain to mtemp */ + mftmp = nfs_setmntent (MOUNTED_TEMP, "w"); + if (mftmp == NULL || mftmp->mntent_fp == NULL) { + int errsv = errno; + nfs_error (_("cannot open %s (%s) - mtab not updated"), + MOUNTED_TEMP, strerror (errsv)); + goto leave; + } + + for (mc = mc0->nxt; mc && mc != mc0; mc = mc->nxt) { + if (nfs_addmntent(mftmp, &(mc->m)) == 1) { + int errsv = errno; + die (EX_FILEIO, _("error writing %s: %s"), + MOUNTED_TEMP, strerror (errsv)); + } + } + +#if 0 + /* the chain might have strings copied from 'instead', + * so we cannot safely free it. + * And there is no need anyway because we are going to exit + * shortly. So just don't call discard_mntentchn.... + */ + discard_mntentchn(mc0); +#endif + if (fchmod (fileno (mftmp->mntent_fp), + S_IRUSR|S_IWUSR|S_IRGRP|S_IROTH) < 0) { + int errsv = errno; + fprintf(stderr, _("error changing mode of %s: %s\n"), + MOUNTED_TEMP, strerror (errsv)); + } + nfs_endmntent (mftmp); + + { /* + * If mount is setuid and some non-root user mounts sth, + * then mtab.tmp might get the group of this user. Copy uid/gid + * from the present mtab before renaming. + */ + struct stat sbuf; + if (stat (MOUNTED, &sbuf) == 0) + chown (MOUNTED_TEMP, sbuf.st_uid, sbuf.st_gid); + } + + /* rename mtemp to mtab */ + if (rename (MOUNTED_TEMP, MOUNTED) < 0) { + int errsv = errno; + fprintf(stderr, _("can't rename %s to %s: %s\n"), + MOUNTED_TEMP, MOUNTED, strerror(errsv)); + } + + leave: + unlock_mtab(); +} diff --git a/support/include/fstab.h b/utils/mount/fstab.h similarity index 100% rename from support/include/fstab.h rename to utils/mount/fstab.h -- 2.39.2